Geology

Some of the world’s expanding coastal cities face a two-pronged threat involving water: Sticking giant straws into the ground to suck up freshwater can cause the ground below to sink at the same time that sea levels are rising.

That interplay between subsiding land and rising seas highlights an underappreciated risk in global climate change, according to scientists.

It’s not known how many people live on coastal lands that are sinking due to excessive groundwater pumping, but about 150 million live within 3.3 feet of today’s high-tide mark. And the worst-case scenario for sea level rise by the end of this century is nearly six feet, according to a recent study.

Earthquakes like the one that woke residents from their beds on March 10 in Poland Township, Ohio, might become a more frequent occurrence in areas where fracking is becoming big business. Scientists are reporting mounting evidence that tremors can be tied to the much-debated drilling technique and related activities. What’s not clear is who might be held responsible for the quakes.

Fracking refers to the method the petroleum industry uses to break apart chunks of shale rock deep within the earth to free trapped oil and gas. Geologists in Ohio established a “probable connection” between fracking and the magnitude 3.0 quake on March 10. In Oklahoma, geologists report a spike in earthquakes associated with injecting into deep underground wells the wastewater generated during fracking operations.

The heightened awareness of seismic activity associated with fracking and wastewater injection raises the question of who is responsible should an earthquake occur that causes damage to people or their property.

A newly discovered volcano rumbling beneath nearly a mile of ice in Antarctica will almost certainly erupt at some point in the future, according to a new study. Such an event could accelerate the flow of ice into the sea and push up the already rising global sea levels.

When the volcano will blow is unknown, “but it is quite likely” to happen, Amanda Lough, a graduate student in seismology at Washington University in St. Louis, Mo., told NBC News.

The rivers of water pumped into and out of the ground during the production of natural gas, oil and geothermal energy are causing the Earth to shake more frequently in areas where these industrial activities are soaring, according to a series of studies published today.

While the gas extraction process known as hydraulic fracturing (aka “fracking”) causes some small quakes, it’s the disposal of wastewater following that process — and many others relating to energy production — that lead to the largest tremors.

“Fortunately, there have been no deaths and damage has been limited to date, but it is obviously of concern to people as we think about the future of the energy economy,” William Ellsworth, a seismologist with the United States Geological Survey in Menlo Park, Calif., told NBC News.

The current boom in U.S. natural gas production from glassy shale rock formations is poised to usher in an era of energy independence and could bridge the gap between today’s fossil-fuel age and a clean-energy future. But that future may be swamped in a legacy of wastewater, a new study suggests.

Natural gas production is soaring thanks to hydraulic fracturing, or fracking, a technique that shoots several million gallons of water laced with chemicals and sand deep underground to break apart chunks of the glassy rock, freeing trapped gas to escape through cracks and fissures into wells.

An average of 10 percent of this water flows back to the surface within a few weeks of the frack job. The rest is absorbed by the surrounding rock and mixes with briny groundwater, explained Radisav Vidic, a civil and environmental engineer at the University of Pittsburgh.

A Florida man is missing after an apparent sinkhole opened in his bedroom in the middle of the night, sucking him and his bed deep into the earth. As frightening as it sounds, sinkholes happen all the time, according to geologists. Usually, though, they are slow-motion processes that can take years.

Sinkholes of the sort that swallowed the Florida man form when slightly acidic groundwater dissolves limestone or similar rock that lies beneath the soil creating a large void or cavities. When the overlying ceiling can no longer support the weight of the soil and whatever is on top of it, the earth collapses into the cavity.